Radio telephone communication systems, such as, for example cellular communication system, may operate according to formal and public standards. The standards may be classified according to generations, for example, first generation (1G), second generation (2G), third generation (3G) or the like. 3G standards may include a standard for Universal Mobile Telecommunication System (UMTS). The UMTS system may be functionally divided into three main parts: User Equipment (UE), UMTS Terrestrial Radio Access Network (UTRAN and Core Network (CN), if desired. The UE may include one or more user's mobile terminals, which may be referred to as Mobile Equipment (ME); the UTRAN may be capable of handling all radio-related functionality; and the CN may be capable of switching and routing calls and data connections to external networks, if desired.
Some of the system units such as, for example, UTRAN and CN, may be operably connected trough interfaces. The interfaces may include physical links, for example, leased lines extending through public areas and/or network infrastructures that are hard to control. User data and some UMTS signaling frames that may by available on some interfaces may not be adequately protected by authentication and integrity means.
It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.